Manufacturing method of secondary batteries
The method of temporary and full-circumferential welding with controlled laser angles and positions addresses the risk of electrode body damage during secondary battery sealing, ensuring secure and efficient sealing.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- PRIME PLANET ENERGY & SOLUTIONS INC
- Filing Date
- 2023-10-11
- Publication Date
- 2026-06-24
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
The laser welding process during the sealing of a secondary battery's battery case can cause heat-induced gaps, leading to potential damage of the electrode body due to laser penetration from these gaps.
A manufacturing method involving temporary welding at selected locations followed by full-circumferential welding, with controlled laser beam angles and positions to prevent laser penetration into the battery case.
Prevents damage to the electrode body by minimizing laser penetration through controlled welding techniques, ensuring efficient and secure sealing without compromising the integrity of the battery case.
Smart Images
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Abstract
Description
Technical Field
[0001] The present technology relates to a method for manufacturing a secondary battery and a secondary battery.
Background Art
[0002] A rectangular secondary battery having a configuration in which an electrode body is housed in a battery case together with an electrolytic solution is disclosed, for example, in Japanese Patent Application Laid-Open No. 2013-187087 (Patent Document 1).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] The battery case of the above-described secondary battery includes a bottomed rectangular cylindrical rectangular outer can having an opening and a sealing plate that seals the opening of the rectangular outer can. The sealing plate is attached to the opening of the battery case by laser welding. During laser welding, due to the influence of heat caused by temperature rise, the gap between the rectangular outer can and the sealing plate increases. As a result, the laser of the laser welding may enter the inside of the rectangular outer can from the gap, and there is a risk of damaging the electrode body in the battery case.
[0005] An object of the present technology is to provide a method for manufacturing a secondary battery and a secondary battery having a configuration that does not damage the electrode body in the battery case when fixing the sealing plate to the opening of the rectangular outer can.
Means for Solving the Problems
[0006] The present technology provides the following method for manufacturing a secondary battery.
[0007] [1] A method for manufacturing a secondary battery, comprising an electrode body, an outer can having an opening, and a sealing plate that houses the electrode body inside the outer can and seals the opening, the method comprising the steps of fixing the sealing plate to the opening using a laser beam, arranging the sealing plate in the opening, performing temporary welding with the laser beam at a plurality of selected locations between the opening and the sealing plate, and then performing continuous full-circumferential welding with the laser beam around the entire circumference between the opening and the sealing plate.
[0008] [2] The method for manufacturing a secondary battery according to [1], wherein, in the step of performing the tack welding, the sealing plate is positioned in the opening of the outer can, and when the sealing plate is viewed from above, the laser beam is irradiated in such a state that the optical axis of the laser beam is inclined from the inside to the outside of the opening.
[0009] [3] The method for manufacturing a secondary battery according to [1] or [2], wherein in the step of performing the tack welding, the optical axis of the laser beam is intersected with the side edge of the sealing plate and the welding is performed while moving from the inside to the outside of the opening.
[0010] [4] The method for manufacturing a secondary battery according to any one of [1] to [3], wherein, in the process of performing the full-circumferential welding, the sealing plate is positioned in the opening of the outer can and the laser beam is irradiated such that the optical axis of the laser beam is perpendicular to the sealing plate.
[0011] [5] The method for manufacturing a secondary battery according to any one of [2] to [4], wherein the outer casing is a rectangular outer casing in the shape of a bottomed rectangular tube having the opening, the length of the rectangular outer casing is 300 mm or more, the plate thickness of the rectangular outer casing is 0.65 mm or less, the spacing of the tack welds is 80 mm or less, in the process of performing the tack welding, the irradiation angle of the laser beam is inclined at approximately 3 degrees or more with respect to the perpendicular to the sealing plate, the laser beam has a core diameter of 0.26 mm to 0.34 mm, the ring diameter of the beam is 0.77 mm to 0.98 mm, the output of the laser beam is 700 (W) to 1000 (W) for the core and 4800 (W) to 7000 (W) for the ring, and the scanning speed of the laser beam is 100 mm / s to 220 mm / s.
[0012] [6] The method for manufacturing a secondary battery according to any one of [1] to [5], wherein the sealing plate includes a first electrode and a second electrode, and the spacing of the tack welds provided around the first electrode and the second electrode is smaller than the spacing of the tack welds provided in other areas.
[0013] [7] The method for manufacturing a secondary battery according to any one of [1] to [6], wherein the secondary battery is a lithium-ion battery.
[0014] This technology provides the following secondary batteries. [8] A secondary battery comprising an electrode body, an outer casing having an opening, and a sealing plate that houses the electrode body inside the outer casing and seals the opening, wherein the space between the sealing plate and the opening includes a full-circumferential weld provided around the entire circumference of the opening, and a plurality of temporary welds provided so as to be in contact with the inside of the full-circumferential weld, and recessed in the thickness direction of the sealing plate.
[0015] [9] The secondary battery according to [8], wherein the sealing plate includes a first electrode and a second electrode, and the spacing of the tack welds provided around the first electrode and the second electrode is smaller than the spacing of the tack welds provided in other areas.
[0016]
[10] The outer can is a bottomed rectangular cylindrical can having the opening, and the battery is a lithium ion battery. The secondary battery according to [8] or [9].
Effect of the Invention
[0017] According to the present technology, when fixing the sealing plate to the opening of the rectangular outer can, it is possible to provide a manufacturing method of a secondary battery and a secondary battery having a configuration that does not damage the electrode body in the battery case.
Brief Description of the Drawings
[0018] [Figure 1] It is a perspective view of the rectangular secondary battery of the present embodiment. [Figure 2] It is a first plan view showing the manufacturing process of the rectangular secondary battery of the present embodiment. [Figure 3] It is a second plan view showing the manufacturing process of the rectangular secondary battery of the present embodiment. [Figure 4] It is a plan view showing details of temporary welding in the manufacturing process of the rectangular secondary battery of the present embodiment. [Figure 5] It is a longitudinal sectional view showing details of temporary welding in the manufacturing process of the rectangular secondary battery of the present embodiment. [Figure 6] It is a flow chart showing the welding process of the present embodiment. [Figure 7] It is a view showing the process of performing temporary welding in the present embodiment. [Figure 8] It is a schematic view showing the irradiation angle of the laser beam in the present embodiment. [Figure 9] It is a schematic view showing the scanning direction of the laser beam in the present embodiment. [Figure 10] It is a view showing the process of performing full circumference welding in the present embodiment. [Figure 11] It is a view showing the irradiation conditions of the laser beam in the present embodiment. [Figure 12] It is a schematic view showing the diameter of the core of the laser beam and the diameter of the beam ring in the present embodiment. [Figure 13]This is a schematic diagram showing the welding state of a comparative example. [Figure 14] This is a schematic diagram showing the welding state of this embodiment. [Figure 15] This diagram schematically shows the gap that forms between the opening and the sealing plate before welding. [Figure 16] This figure shows the evaluation results of the total output (W) of the laser beam and the change in the gap between the aperture and the sealing plate. [Figure 17] This figure evaluates whether or not laser penetration occurs when no temporary weld is provided. [Figure 18] This diagram evaluates whether or not laser penetration occurs when a temporary weld is provided. [Figure 19] This figure shows the evaluation of laser beam penetration as a result of the laser beam irradiation angle when a temporary weld is made. [Modes for carrying out the invention]
[0019] Embodiments of this technology are described below. Note that the same or corresponding parts may be denoted by the same reference numerals, and their descriptions may not be repeated.
[0020] In the embodiments described below, when referring to the number, quantity, etc., the scope of this technology is not necessarily limited to that number, quantity, etc., unless otherwise specified. Also, in the embodiments described below, each component is not necessarily essential to this technology unless otherwise specified.
[0021] In this specification, the terms "comprise," "include," and "have" are in open-ended form. That is, if a certain configuration is included, other configurations may or may not be included. Furthermore, this technology is not necessarily limited to achieving all of the effects mentioned in this embodiment.
[0022] Where geometric terms and terms describing positional and directional relationships are used herein, such as "parallel," "orthogonal," "45° oblique," "coaxial," and "alongside," these terms allow for manufacturing tolerances or slight variations. Where terms describing relative positional relationships, such as "upper" and "lower," are used herein, these terms are used to indicate the relative positional relationship in a single state, and the relative positional relationship may be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by inverting the entire mechanism upside down).
[0023] In this specification, “secondary battery” is not limited to lithium-ion batteries, but may include other secondary batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, “electrode” may refer collectively to the positive electrode and the negative electrode.
[0024] In the drawings, the width direction (left-right direction on the page) of the rectangular casing of the secondary battery is the X direction, the thickness direction (depth direction on the page) is the Y direction, and the height direction (up-down direction on the page) is the Z direction, with the X, Y, and Z directions being mutually orthogonal. To facilitate understanding of the invention, some of the dimensions of the components in the drawings have been altered from the actual dimensions.
[0025] Referring to Figures 1 to 5, the configuration of a prismatic secondary battery will be described as an example of a secondary battery in this embodiment. Figure 1 is a perspective view of a prismatic secondary battery, Figure 2 is a first enlarged photograph showing the welding state between the outer casing and the sealing plate, Figure 3 is an enlarged longitudinal cross-sectional view of Figure 2, Figure 4 is a second enlarged photograph showing the welding state between the outer casing and the sealing plate, and Figure 5 is an enlarged longitudinal cross-sectional view of Figure 3.
[0026] This secondary battery 1 includes a battery case 100, an electrode body 200, a first electrode 400 (positive terminal), a second electrode 500 (negative terminal), and a sealing member 900.
[0027] The battery case 100 has a rectangular outer casing 110, which is a bottomed rectangular tubular shape with an opening 110h, and a sealing plate 120 that seals the opening 110h of the rectangular outer casing 110. The rectangular outer casing 110 and the sealing plate 120 are preferably made of metal, and preferably of aluminum or an aluminum alloy. The external dimensions of the rectangular outer casing 110 are preferably a width of 30 mm or more, a length of 300 mm or more, and a plate thickness of 0.65 mm or less. The external dimensions of the sealing plate 120 are preferably a width of 30 mm or more, a length of 300 mm or more, and a thickness of 2 mm or less.
[0028] The sealing plate 120 is provided with an electrolyte injection hole 121. After the electrolyte is injected into the battery case 100 through the electrolyte injection hole 121, the electrolyte injection hole 121 is sealed by a sealing member 900 (such as a rivet).
[0029] A gas release valve 122 is provided in the sealing plate 120. The gas release valve 122 ruptures when the pressure inside the battery case 100 exceeds a predetermined value. This causes the gas inside the battery case 100 to be released to the outside of the battery case 100.
[0030] The electrode assembly 200 is housed in the battery case 100 along with the electrolyte. The electrode assembly 200 consists of a positive electrode plate and a negative electrode plate stacked with a separator in between. A resin insulating sheet (not shown) is placed between the electrode assembly 200 and the rectangular outer casing 110.
[0031] The first electrode 400 is fixed to the sealing plate 120 via an external insulating member 410 made of resin. The second electrode 500 is fixed to the sealing plate 120 via an external insulating member 510 made of resin.
[0032] The first electrode 400 is preferably made of metal, and more preferably of aluminum or an aluminum alloy. The second electrode 500 is preferably made of metal, and more preferably of copper or a copper alloy.
[0033] A sealing plate 120 is fixed to the opening 110h of the rectangular outer container 110 by welding. Between the sealing plate 120 and the opening 110h, there is a full-circumference welded section WH provided around the entire circumference of the opening 110h, and multiple temporary welded sections WK provided in contact with the inside of the full-circumference welded section WH, which are recessed in the thickness direction of the sealing plate 120. The locations where the temporary welded sections WK are provided will be explained later in the welding method section, but depending on the size of the temporary welded sections WK, there may be places where the temporary welded sections WK are covered by the full-circumference welded section WH.
[0034] As shown in Figures 2 and 3, when the inward protrusion G1 of the circumferential weld WH of the temporary weld WK is large, the surface of the temporary weld WK exhibits a curved shape that is recessed in the thickness direction of the sealing plate 120. As shown in Figures 4 and 5, when the inward protrusion G1 of the circumferential weld WH of the temporary weld WK is small, the surface of the temporary weld WK can be seen as a recessed shape where the groove 120G provided on the side of the sealing plate 120 is exposed.
[0035] (Welding process of sealing plate 120 to opening 110h of rectangular outer container 110) Next, with reference to Figures 6 to 14, the manufacturing method of a secondary battery will be described, specifically the welding process of the sealing plate 120 to the opening 110h of the rectangular outer casing 110. Figure 6 is a flowchart showing the welding process, Figure 7 is a diagram showing the tack welding process, Figure 8 is a schematic diagram showing the laser beam irradiation angle, Figure 9 is a schematic diagram showing the laser beam scanning direction, Figure 10 is a diagram showing the full-circumference welding process, Figure 11 is a diagram showing the laser beam irradiation conditions, Figure 12 is a schematic diagram showing the core diameter and ring diameter of the laser beam, Figure 13 is a schematic diagram showing the welding state of a comparative example, and Figure 14 is a schematic diagram showing the welding state of this embodiment.
[0036] Referring to Figure 6, the welding process of the sealing plate 120 to the opening 110h of the rectangular outer container 110 includes the steps of: confirming the fitting gap between the opening 110h and the sealing plate 120 (S10); inserting the can and placing the sealing plate 120 on the opening 110h (S20); clamping the tack welded portion (S30); performing tack welding (diagonal welding) (S40); clamping the entire surface (S50); and performing final welding (full circumference welding) (S60).
[0037] Referring to Figure 7, a sealing plate 120 is placed in the opening 110h, and tack welds WK are provided by laser welding at a selection of locations between the opening 110h and the sealing plate 120. In this embodiment, when the external dimensions of the battery case 100 in plan view are 300 mm in the width direction (X direction) and 40 mm in the width direction (Y direction), the locations where tack welds WK are provided are 6 locations on each side of the opening 110h in the width direction (X direction), for a total of 12 locations. In the width direction (Y direction) of the opening 110h, tack welds WK are provided at 2 locations on each side, for a total of 4 locations. Therefore, 16 tack welds WK (WK1 to WK16) are provided around the entire circumference of the opening 110h.
[0038] In this embodiment, the sealing plate 120 is provided with a first electrode 400 and a second electrode 500, and the spacing of the temporary fixation around the first electrode 400 and the second electrode 500 is smaller than the spacing of the temporary fixation in other areas. In this embodiment, the spacing of the temporary fixation around the gas discharge valve 122 is smaller than the spacing of the temporary fixation in other areas, but the spacing of the temporary fixation around the gas discharge valve 122 may be the same as the spacing of the temporary fixation in other areas.
[0039] In this embodiment, in the width direction (X direction) of the sealing plate 120, when the gas discharge valve 122 is provided at the center CL position of the sealing plate 120 in the width direction (X direction), temporary welds WK (WK3,4,11,12) are provided at a distance L2 (20 mm in this embodiment) from the center CL, temporary welds WK (WK2,5,10,13) are provided at a distance L1 (80 mm in this embodiment) from these temporary welds WK, and further temporary welds WK (WK1,6,9,14) are provided at a distance L3 (20 mm in this embodiment) from these temporary welds WK. In the thickness direction (Y direction) of the sealing plate 120, temporary welds WK (WK7,8,15,16) are provided at a distance L4 (5 mm in this embodiment) from the side edge. The spacing between adjacent temporary welds WK is preferably 80 mm or less.
[0040] As a result, many temporary welds WK are provided around the first electrode 400 and the second electrode 500. By providing many temporary welds WK around the first electrode 400 and the second electrode 500 in this way, it becomes possible to pre-position the opening 110h of the rectangular outer container 110 and the sealing plate 120 in the height direction (Z direction). As a result, the height accuracy required during busbar welding in the subsequent process can be satisfied.
[0041] Referring to Figure 8, the optical axis of the laser beam LB when forming the temporary weld WK is irradiated with an inclination from the inside to the outside of the opening 110h. The irradiation angle θ of the laser beam LB should be inclined at approximately 3 degrees or more with respect to the perpendicular VL to the sealing plate 120. By inclining the irradiation angle θ of the laser beam LB from the inside to the outside of the opening 110h in this way, even if the laser beam LB enters the interior of the rectangular outer container 110 through the gap between the sealing plate 120 and the opening 110h, it is possible to prevent the laser beam LB from directly irradiating the electrode body 200 housed inside the rectangular outer container 110.
[0042] Referring to Figure 9, in a plan view, when forming the temporary weld WK, the scanning direction of the laser beam LB should intersect with the side edge 120a of the sealing plate 120, and welding should be performed while moving from the inside to the outside of the opening 110h. In this embodiment, the intersection angle with the side edge 120a of the sealing plate 120 should be about 45 degrees, and the scanning distance D1 in the width direction (X direction) and the scanning distance D2 in the thickness direction (Y direction) should both be about 0.7 mm.
[0043] Referring to Figure 10, after forming a temporary weld WK, the entire circumference between the opening 110h and the sealing plate 120 is continuously welded with a laser beam LB to form a full-circumference weld WH. In forming the full-circumference weld WH, a single continuous weld is preferable for quality assurance and cycle time, and for this purpose, it is preferable that the laser beam is irradiated with the optical axis of the laser beam perpendicular to the sealing plate 120. In particular, in this embodiment, since a temporary weld WK is provided in the previous step, even if the optical axis of the laser beam is perpendicular to the sealing plate 120, welding without laser leakage is possible during full-circumference welding.
[0044] Referring to Figures 11 and 12, the conditions for the laser beam LB in tack welding and full-circumference welding will be described. A ring-mode laser is used for the laser beam LB. The diameter of the core LB1 of the laser beam LB is preferably 0.26 mm to 0.34 mm, and the diameter of the ring LB2 of the beam is preferably 0.77 mm to 0.98 mm.
[0045] The core output (W) during tack welding is preferably 700 (W) to 1000 (W), the ring output (W) is preferably 4800 (W) to 7000 (W), the scanning speed (mm / s) is preferably 100 mm / s to 220 mm / s, the irradiation angle (degrees) is preferably 8 degrees or less, and the spacing of the tack welds (mm) is preferably 80 mm or less.
[0046] The core output (W) during the actual welding is preferably 1600 (W) to 2000 (W), the ring output (W) is preferably 3800 (W) to 5000 (W), and the scanning speed (mm / s) is preferably 240 mm / s to 380 mm / s.
[0047] Referring to Figure 12, in welding between the opening 110h and the sealing plate 120, if the scanning direction of the laser beam LB is S1, and the rectangular outer container 110 and the sealing plate 120 are made of aluminum, a molten aluminum pool R1 is formed upstream of the moving laser beam LB. By irradiating the aluminum with the laser beam LB across this molten pool R1 and further melting the aluminum, it is possible to prevent the laser from entering the middle of the rectangular outer container 110 (laser bleed). Subsequently, by moving the laser beam, the molten aluminum is cooled and solidified, and a welded area R2 is formed downstream.
[0048] Referring to Figure 13, when full-circumference welding is started between the opening 110h and the sealing plate 120, it is conceivable that the gap between the opening 110h and the sealing plate 120 will increase due to thermal distortion of the laser beam LB. As the gap increases, the risk of the laser entering the interior of the rectangular outer container 110 increases.
[0049] On the other hand, as shown in Figure 14, in this embodiment, by providing a temporary weld WK between the opening 110h and the sealing plate 120 in advance before starting full-circumferential welding, it is possible to suppress the increase in the gap between the opening 110h and the sealing plate 120 due to thermal distortion of the laser beam LB. This makes it possible to suppress the penetration of the laser into the interior of the rectangular outer container 110.
[0050] Furthermore, in the case of full-circumference welding shown in Figure 13, a method was sometimes adopted in which the full-circumference welding was divided into several stages with cooling periods in order to suppress the expansion of gaps due to thermal distortion of the laser beam LB. However, dividing the full-circumference welding into several stages increases the time required for full-circumference welding. However, in this embodiment, the full-circumference welding process is completed in one stage, thus shortening the time required for full-circumference welding. This makes it possible to improve the efficiency of the secondary battery manufacturing process.
[0051] (Evaluation results) The evaluation results of the secondary battery 1 described above will be explained below with reference to Figures 15 to 19. Figure 15 is a schematic diagram showing the gap between the opening 110h and the sealing plate 120 before welding, Figure 16 is a diagram showing the evaluation results of the total output (W) of the laser beam and the change in the gap between the opening and the sealing plate, Figure 17 is a diagram evaluating the presence or absence of laser leakage when no tack weld is provided, Figure 18 is a diagram evaluating the presence or absence of laser leakage when a tack weld is provided, and Figure 19 is a diagram showing the evaluation of laser leakage with respect to the irradiation angle of the laser beam when a tack weld is provided.
[0052] Referring to Figure 15, the gap (before welding) between the opening 110h and the sealing plate 120 used in the evaluation described below will be explained. The square outer container 110 with the opening 110h and the sealing plate 120 were the same as described above. Before welding, the end face T1 of the opening 110h and the end face T2 of the sealing plate 120 each have a wavy surface, and the dimensional tolerance of each end face is ±0.05 mm. Therefore, the maximum gap S1 between the end face T1 of the opening 110h and the sealing plate 120 is approximately 0.2 mm.
[0053] In the evaluations described below, tack welding and full-circumference welding were performed sequentially, and the amount of gap increase during welding and the presence or absence of laser leakage were evaluated. A ring-mode laser, consisting of a core and a ring as shown in Figure 12, was used for the laser beam. The laser welding conditions for tack welding and full-circumference welding were the laser conditions shown in Figure 11. Tack welding was performed under the conditions shown in Figures 8 and 9.
[0054] Referring to Figure 16, the evaluation results of the total laser beam output (W) and the change in the gap between the opening and the sealing plate will be explained. In the figure, the horizontal axis shows the total laser beam output (W), and the vertical axis shows the increase in the gap. The total laser beam output (W) is the sum of the core output and the ring output. In the figure, S1 shows the evaluation results when a tack weld is provided in the case where the can thickness of the square outer can 110 is 0.65 mm (this embodiment), S2 shows the evaluation results when a tack weld is not provided in S1 (comparative example), and S3 shows the evaluation results when a tack weld is not provided in the case where the can thickness of the square outer can 110 is 0.8 mm (comparative example).
[0055] As shown in the evaluation results in Figure 16, comparing S2 and S3, it was found that when the can thickness is small, the size of the gap between the opening and the sealing plate increases as the total output of the laser beam increases. However, as shown in S1, it was confirmed that the increase in the gap between the opening and the sealing plate can be suppressed by providing a temporary weld.
[0056] Referring to Figures 17 and 18, the occurrence of laser bleed was confirmed when a gap of 0.2 mm was created between the opening and the sealing plate before welding, with and without a tack weld (Figure 17) and with a tack weld (Figure 18). In the figures, the horizontal axis shows the core output of the laser beam, and the vertical axis shows the ring output of the laser beam.
[0057] In the case where no temporary weld is provided as shown in Figure 17, laser beam ring output and core output were appropriately combined (6 locations) to check for laser beam dropouts, but laser beam dropouts were observed in all combinations (locations indicated by "×" in the figure). On the other hand, as shown in Figure 18, laser beam dropouts were checked with the same combination of laser beam ring output and core output as shown in Figure 17, but no laser beam dropouts were observed in any combination (locations indicated by "○" in the figure). By comparing Figure 17 and Figure 18, it was confirmed that laser beam dropouts can be suppressed by providing a temporary weld.
[0058] Referring to Figure 19, the horizontal axis shows the irradiation angle (°) of the laser beam when forming the tack weld, and the vertical axis shows the size of the gap between the opening and the sealing plate. This allowed us to evaluate the laser dropout with respect to the irradiation angle when forming the tack weld. The guaranteed gap on the equipment side that does not cause laser dropout is 0.05 mm. The inclination angle here is the irradiation angle θ shown in Figure 8.
[0059] The area above line BL1 in the diagram indicates the region where the laser beam may directly penetrate (insert) into the rectangular outer casing 110 through the gap. The area below line BL2 in the diagram indicates the region where the laser beam does not penetrate into the rectangular outer casing 110 through the gap. The "×" mark in the diagram indicates that laser beam leakage occurred, and the "○" mark indicates that laser beam leakage did not occur.
[0060] As shown in Figure 19, the irradiation angle θ of the laser beam when forming the tack weld is preferably 3 degrees or more in order to guarantee the equipment-side guaranteed gap of 0.05 mm as described above.
[0061] While embodiments of the present technology have been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present technology is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]
[0062] 1 Secondary battery, 100 Battery case, 110 Rectangular outer casing, 110h Opening, 120 Sealing plate, 120G Groove, 120a Side edge, 121 Electrolyte injection hole, 122 Gas discharge valve, 200 Electrode body, 400 First electrode, 410, 510 External insulating member, 500 Second electrode, 900 Sealing member.
Claims
1. Electrode body and An outer can having an opening, The electrode body is housed inside the outer can, and a sealing plate is provided to seal the opening, A method for manufacturing a secondary battery, comprising: The process includes fixing the sealing plate to the opening using a laser beam, The process involves placing the sealing plate in the opening and performing temporary welding at a plurality of selected locations between the opening and the sealing plate using the laser beam. Subsequently, the process involves continuously welding the entire circumference between the opening and the sealing plate using the laser beam, It has, In the process of performing the aforementioned tack welding, With the sealing plate positioned in the opening of the outer can, when the sealing plate is viewed from above, the laser beam is irradiated with the optical axis of the laser beam tilted from the inside to the outside of the opening. With the sealing plate positioned in the opening of the outer can, when the sealing plate is viewed from above, the scanning direction of the laser beam intersects with the side edge of the sealing plate and moves from the inside to the outside of the opening. A method for manufacturing secondary batteries.
2. In the process of performing the aforementioned full-circumference welding, With the sealing plate positioned in the opening of the outer can, the laser beam is irradiated such that its optical axis is perpendicular to the sealing plate. A method for manufacturing a secondary battery according to claim 1.
3. The outer container is a rectangular outer container with a bottom and a rectangular shape having the opening, The length of the aforementioned rectangular outer container is 300 mm or more. The plate thickness of the aforementioned rectangular outer container is 0.65 mm or less. The spacing of the aforementioned tack welds is 80 mm or less. In the process of performing the aforementioned tack welding, The irradiation angle of the laser beam is inclined at approximately 3 degrees or more with respect to the perpendicular line to the sealing plate. The laser beam has a core diameter of 0.26 mm to 0.34 mm and a ring diameter of 0.77 mm to 0.98 mm. The laser beam has an output of 700 W to 1000 W for the core and 4800 W to 7000 W for the ring. The scanning speed of the laser beam is between 100 mm / s and 220 mm / s. A method for manufacturing a secondary battery according to claim 1 or claim 2.
4. The sealing plate includes a first electrode and a second electrode, The spacing of the tack welds provided around the first electrode and the second electrode is smaller than the spacing of the tack welds provided in other areas. A method for manufacturing a secondary battery according to claim 1.
5. The aforementioned secondary battery is a lithium-ion battery. A method for manufacturing a secondary battery according to claim 1.